The clinical syndrome of multiple personality disorder (MPD) is an unusual dissociative disorder that previously had been poorly characterized. Systematic data have been collected on over 200 recent cases of MPD in treatment in the United States. Results indicate that MPD is a clinical syndrome with a core of dissociative and depressive symptoms that occurs in individuals with a history of childhood trauma between ages 2 and 14 years. Male and female MPD patients differ on the expression of aggressive and self-destructive symptoms.